Botanists counted among flowering plants more than 360 thousand species.And this matter is not over.Flowers are found from the tropics to the tundra - in all climatic zones of the planet.They are everywhere: in deserts, forests, steppes, marshes and lakes, on the coast and in the highlands.This flowering plant make up the bulk of matter of the biosphere.Thanks to them, produced plant foods - cereals, most fruits and vegetables, berries and nuts.
most important element of the angiosperms (flowering the second name) is a flower.The main parts of a flower - a pistil and stamens.Through a complex process of pollination and fertilization with their participation form seeds - the continuation and evolution of plant life on the planet.
Flower: structure and function
higher plants are composed of the root, stem with leaves and flowers, which are shortened and modified stem.The root, stem and leaves - vegetative parts that are responsible for plant growth.Flower - generative element, reproductive organs.Usually attached to the flowers pedicels - so called sophisticated part of the stem without leaves.Some plants pedicels absent or barely expressed.It - sessile flowers.Pedicel expands, moving into the receptacle.
's list from the bottom up, from the peduncle, the main parts of a flower.This receptacle, which is the basis for the placement of the remaining elements of the flower.Receptacle can be of various shapes, from the conical, like a magnolia, to a flat (chamomile) or even concave (rose hips), starting with a cup, which is formed by the sepals.Typically, they are green, but can be brightly colored.Calyx can be single-row or epicalyx formed from the second round of the sepals.Next - the corolla of the flower, composed of petals.A variety of flower corolla large: color, color intensity, size, number, shape, mutual arrangement, cleavage petals.
Collectively, the sepals and petals make up the perianth - cover the flower.Some have flowered petals and they do not differ from the sepals.In such cases, the perianth is simple;It called double if there sepal and petals.Perianth - sterile appendage flower.Features flowers assigned to perianth - protection carpel (pistil or carpel) and guarantee pollination.Bright colors and attractive smell corolla provide visiting plants by insects.
The bracts are fertile, at least the major part of the flower.It gynoecium, easier - the pistil, which developed ovules with a receptacle for the gametophyte (megaspores).It is the female sexual organ of a flower.The bracts and is the male sexual organ, which the structural unit - stamen.Collectively called the stamen androecium.The stamen anthers formed microspores.Of them receive pollen grain - male gametophyte.
main part
flower pistil and stamens are essential elements, since they - distribution of male and female sex cells.It - gametophytes, a substance which arises from the confluence of the seed, and the fruit of flowering.Pestle (correct to call it a carpel) consists of the ovary, a column (some flowering itself is not), and stigma.In the ovary there embryo sac with its target ovules.The top of the column ends with the stigma, where pollen is delayed.It is produced in the stamens (mikrosporolistikah).Typical stamen consists of two parts: Filaments (sterile, barren part) and anther fertility (fertility) function.
monoecious and dioecious
About 75% of the species of angiosperms are hermaphroditic (hermaphroditic) flowers - they have, and the stamens and pistils.These plants are monoecious (example - corn).There are plants in which some individuals - with only staminate flowers, and others - only pistillate.They are called dioecious (example - hemp).
pollination
essence pollination is getting pollen on the stigma of the stamens.It can be self-pollinated, a classic example of which is seen in undisclosed flowers (some kinds of violets, peanuts, barley).The second way - cross-pollination that occurs in most flowering.Some carriers of pollen: wind, water, insects, ants, birds.
Double fertilization
At the confluence of the male gametes (sperm) from the female gamete (egg) fertilization occurs.To do this, you need to on the stigma, moist sticky sweet liquid, sprouted pollen stamens.Have sprouted speck starts growing pollen tube - a very long and very thin.It penetrates into the ovary close to the ovules.At the end of the tube attached to two sperm.Ovule, consisting of cells develop within the ovary.The egg is close to pyltsevhodu, which penetrates pyltsetrubka.Other cells, secondary, located in the center of the ovary.Pyltsetrubka bursts and both sperm from her face.One enters the cytoplasm and nucleus fuses with the egg cell, and the other - penetrates into the secondary cell.Fertilization occurs and the egg begins to divide repeatedly by which develops the germ of the plant.Secondary cells and fertilized and begin to divide to form the endosperm - the pantry stock supply to the fetus.This forms a seed.
briefly about the function of flowers
flowering plants in the flora of the planet occupied a leading position in its development, as well as among mammals fauna.Purpose of all living things - to extend their family, to create its continuation.The same eager and flowering.Their reproductive organs, performs the function of reproduction, are flowers.The main parts of a flower - a gynoecium (pistil) and androecium (stamens), that form the sex cells - gametes.In the flowers after pollination to have intercourse - copulation of gametes.As a result of double fertilization of ovules in the ovary developing seeds peel with a reserve of nutrients.This is - the beginning of a new life of future generations in families of flowering plants.
